While there is excitement about the potential of renewable technologies such as tidal power, there are challenges when it comes to scaling up.

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The U.S. Department of Energy said $35 million in funding would be made available “to advance tidal and river current energy systems” under plans it hopes will provide a shot in the arm to a sector whose current footprint is tiny.

In a statement Tuesday outlining the move, the DOE said the funding opportunity — which is slated for release in 2023 — represented the “largest investment in tidal and river current energy technologies in the United States.”

A notice of intent related to the funding opportunity has been posted online. The DOE said it proposed “to develop a tidal or river current research, development, and demonstration site and to support in-water demonstration of at least one tidal energy system.”

Alejandro Moreno, who is acting assistant secretary for Energy Efficiency and Renewable Energy, said oceans and rivers represented “a huge potential source of renewable energy.” The DOE said the funding would come from the Bipartisan Infrastructure Law.

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Over the past few years a number of projects related to tidal power, including ones in the United States, have taken significant steps forward.

In July 2021, for instance, a tidal turbine dubbed “the world’s most powerful” started grid-connected power generation at the European Marine Energy Centre in Orkney, an archipelago located north of mainland Scotland.

In May 2022, a £4.6 million (around $5.18 million) facility that can test tidal turbine blades under strenuous conditions was officially opened, with those behind it hoping it will accelerate the development of marine energy technology and lower costs.

While there is excitement about the potential of renewable technologies such as tidal power, there are significant challenges when it comes to scaling up, a point the DOE acknowledged in its announcement.

“The U.S. tidal and river current energy industry requires long-term and substantial funding to move from testing devices one at a time to establishing a commercial site,” it said.

“The complexity of installing devices and navigating permitting processes, combined with a lack of connection to local power grids, have proven to be a consistent barrier to advancing tidal and river current energy.”

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According to preliminary figures from the U.S. Energy Information Administration, in 2021 fossil fuels’ share of utility-scale electricity generation was 60.8%. By contrast, renewables’ share stood at 20.1%, while nuclear accounted for 18.9%.

While tidal barrage developments were the initial focus of those operating in the marine energy industry — EDF’s La Rance tidal barrage dates back to the 1960s, for example — recent years have seen companies focus their attention on different systems.

These include tidal stream devices which, the European Marine Energy Centre says, “are broadly similar to submerged wind turbines.” Compared to other renewables, the overall size of tidal stream and wave energy projects is very small.

In data released in March 2022, Ocean Energy Europe said 2.2 MW of tidal stream capacity was installed in Europe last year, compared to just 260 kilowatts in 2020.

For wave energy, 681 kW was installed, which OEE said was a threefold increase. Globally, 1.38 MW of wave energy came online in 2021, while 3.12 MW of tidal stream capacity was installed.

By way of comparison, Europe installed 17.4 gigawatts of wind power capacity in 2021, according to figures from industry body WindEurope.